Northern Research Station News Releases

In Southeast Michigan and Northwest Ohio Counties, Scientists Looking for Healthy Ash Trees

Healthy green ash tree in Webberville, Michigan, 2005.  Photo by Therese Poland, US Forest Service Northern Research Station Delaware, OH, October 17, 2014 - A few years ago, Kathleen Knight, a research forester with the USDA Forest Service’s Northern Research Station, was walking back to her car after inventorying ash trees in a research plot at Oak Openings Metropark in Swanton, Ohio. All of the ash trees that she had been monitoring had been killed by emerald ash borer, but just outside of her research plot, Knight was startled to find a perfectly healthy ash tree.

The tree inspired Knight and her colleague, Jennifer Koch, a research biologist with the Northern Research Station, to investigate exactly how some ash trees are surviving EAB, a non-native invasive insect that has killed millions of trees since it was first discovered in 2002. Their initial research involved survivor ash trees they discovered or heard about from other scientists, but Knight and Koch are now looking for citizens’ help in finding survivor ash trees. This week, the Northern Research Station launched a new an on-line system for reporting the location of survivor ash trees in 10 southeast Michigan counties and 7 northwest Ohio counties:

Visitors to the survivor ash page can identify the general location of a tree by entering an address, zip code, latitude and longitude, or even a place name, such as the name of a forest, park or wildlife refuge. Google Maps shows the area, and from there users can zoom in using either map view or satellite view until they can pinpoint a tree’s location and mark the spot with a digital “thumbtack.” 

 “To understand the mechanisms of resistance, we need to study more than just a few survivors,” Knight said. “We need to be able to look at different species as well as genetic diversity within the same species.”

To assure that trees reported to the site are true EAB survivors and not just lucky enough to not yet be infested, Knight and Koch are limiting ash reporting to counties that have been hit hard by EAB. As the insect continues to spread, they expect to open the survivor ash reporting system to additional locations. Trees reported through the system should be natural ash trees rather than planted ash trees, and they should be 10 inches or more in diameter. Ash trees treated with insecticide to prevent EAB should not be reported.

As survivor ash trees and their locations are identified, Knight, Koch and Ohio State University partners will identify the most promising trees and then collect cuttings (small branches or twigs), which Koch will propagate in a greenhouse. Taking cuttings is relatively non-invasive and will not result in harm to the ash trees. When propagated trees in the lab are big enough, EAB eggs will be placed on the trunk and scientists will study how the trees respond to the insect.   

“Over the past two decades, emerald ash borer has changed forest landscapes and has been especially devastating to the ash trees in urban forests,” said Michael T. Rains, Director of the Northern Research Station and the Forest Products Laboratory. “The Forest Service is helping cities and states prepare for and recover from EAB invasion with research on the insect, ash trees’ resistance to EAB, and management strategies.”    

One of seven USDA Forest Service research stations, the Northern Research Station includes 20 states stretching from Maine to Minnesota and from Missouri to Maryland. The Station’s mission ipeople’s lives and help sustain the natural resources in the Northeast and Midwest through leading-edge science and effective information delivery.

The U.S. Forest Service is an agency of the U.S. Department of Agriculture, a mission of sustaining the health, diversity and productivity of the nation’s forests and grasslands to meet the needs of present and future generations. The mission of the Forest Service's Northern Research Station is to improve people’s lives and help sustain the natural resources in the Northeast and Midwest through leading-edge science and effective information delivery.

The U.S. Forest Service manages 193 million acres of public land, provides assistance to state and private landowners, and maintains the largest forestry research organization in the world. Public lands the Forest Service manages contribute more than $13 billion to the economy each year through visitor spending alone. Those same lands provide 20 percent of the nation’s clean water supply, a value estimated at $7.2 billion per year. The agency has either a direct or indirect role in stewardship of about 80 percent of the 850 million forested acres within the U.S., of which 100 million acres are urban forests where most Americans live. For more information, visit


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Last modified: October 17, 2014